Hello all. New to the Jag forums, but not to fixing cars and problem solving. This problem has me baffled. I have been reading numerous forums and many people have experienced this issue, but nothing I do can resolve it, so here it goes:

Stock stereo display has been out for awhile, so decided to swap it with a new aftermarket one. Upon turning car back on I get Gear Box Fault error on the cluster and car wont turn over. I have had absolutely NO issues with this vehicle. Been driving it for a year and a half, put it in the garage, swapped the stereo and "BAM" dead in the water....I figure I must have activated the immobilizer and now it wont run. After many days of searching things to look at, I will tell you what i have looked at / done with no avail:

1. Put old stereo back in. ( I did not cut wiring harness, used a Metra harness for the install)
2. Checked / replace battery (GOOD)
3. Removed Positive / Negative with the touch to rest ECU.
4 Reset inertia switch on passenger footwell.
5. Purchased OBD reader to reset codes. Still show P1638 / P1000 / P1699. These codes stay even after hard reset and clearing on OBD reader.
6. New battery for Key
7. Tested EVERY fuse in engine compartment and in drivers footwell. All good.
8. One forum member talked about jumping starter relay in engine bay to get it to start. This actually got the starter to turn the engine, but it didn't fire, so thinking theft deterrent.

So, there you have it, Its been a daily driver for a year and a half. ZERO issues until pulling that darn stereo. I know its not mechanical, obviously I screwed something up when removing the stock stereo, but super frustrating to think a car would go "dead" just by removing it.

Its probably so simple that I'm missing it, but i tried to work back words from what I did and all of the suggestions on other threads. Totally at a loss.

Thanks for your time and hoping a simple solution is out there.

Ben

 

oops..forgot something. I lied about the fused. Fuse #79 in the drivers side footwell is not getting any juice. It says automatic transmission only.

 

Jammin02, can you give us a little more info about the car. Ie, year, some of the bigger options (ie, DSC, Nav system, manual/stick, or anything else that you think might be important). This is going to help us get down to exactly how your car is wired.

But, from the sounds of things, you have damaged the CAN wiring between the instrument cluster and the ECU/ECM. This most likely happened in the area around the J-gate (shifter) or the area under the radio.

Now, this is all based on me assuming that because your name is Jammin02, that you have a 2002 X-Type. I know you have an earlier car because you talk about fuse 79, the newer cars do not have fuses with numbers that high.

Keep in mind that there are 2 data networks that run through the factory radio. So, undoing the radio and not installing the applicable jumpers can have a detrimental effect on the car.

 

You have damaged the wiring loom between the instrument cluster and ecu.
Check the wiring carefully for any damage, I suspect this happened when you removed the radio cluster.

Paul.

 

Hello Thermo and Man on the Hill. Thank you for the quick replies. Yes, sorry I did not clarify the year and options on the Jag...rookie mistake. I took both of your suggestions and went back and took everything apart to square one. I am really careful when it comes to these things, so I did inspect all the wires and corresponding plugs and everything seemed okay. So I started at the top of the stack with the heated seat plugs, and went down, turning the ignition on each time. I noticed that I had not "clicked" the white climate control plug completely back using the attached lever like the black plug. Success! It fired right up! So for some reason, the climate control plugs will throw a GEAR FAULT and stop the car from starting?

I did reinstall the stock stereo, then removed it and replaced with the aftermarket stereo and we are all good!

I will put a quick post in the appropriate section showing the stereo. Its a nice Nakamichi with all the bells and whistles and has a steering wheel interface built in so the steering controls work as well.

Sorry for such a bonehead post...completely feel like a dummy. I do appreciate the feedback on this. This what makes these forums so worthwhile.

 

Jammin02, bah, we all do these things. Stick around and participate. You now have a tidbit of information from first hand knowledge that may help someone else later on. How do you think some of us know what we know. We had to suffer through the same thing, fight like hell to understand what is going on and then go from there.

To give you a better understanding of what happened, there is a computer network in your car call a CAN (controller area network) that ties all the main computers of the car together (ie, engine computer, tranny computer, instrument cluster, A/C, etc). . The information that the car needs and generates at each of these modules travels back and forth on these 2 wires (one transmits the info, the other receives the info) If you break this network, then the necessary information cannot make it where it needs. So, for example (in your case), the instrument cluster is at one end of the CAN network and the engine computer is at the other. When you turn the key to start the car, you have 2 signals that get generated. You have a 12 VDC signal sent straight to the ECU to say that it is requesting to start the car. The second signal comes from a computer chip in your key that then sends its signal to an antenna that is located around the ignition switch. This key number then gets received by the car, sent up to the instrument cluster. The instrument cluster then takes the number, puts it on the CAN network, where the number makes it way over to the security module which then sees if that number is on the list that it has of good numbers (keys). If that checks out, then the security module sends a command over to the ECU to say that the security side of things checks out and to start the car. Once the ECU sees both the 12VDC signal and the security module message, then it finally says start the car. But, keep in mind, the key number and start message may have gone through 20 modules in the car. Any one of them not plugged in correctly would cause the key number/start message to not make it through, therefore not allowing the car to start. Never thought starting a car could be made so complicated.

 

Thank you for the detailed information. I enjoy the "why things don't work" responses. Never to old to learn! All my instincts said it had to be in there somewhere, but guess I over thought it too much and started to panic. Been working on older cars with less electronics I guess...the Corvette and Mercedes are dinosaurs when in comes to computer brains in comparison. The stereo looks and works great btw. I did a quick post on that yesterday, As long as I have the Jag I'll be jumping on these forums.

Besides the stereo install I've done the water pump, serpentine belt, brakes and washer fluid bottle repair. If I see anyone needing help in these areas I'll be more than happy to help with what I learned. Hooking up the stereo controls was a fun challenge when all said an done.

Thanks again and will hopefully chat again.